This definition is intended to include frames having systems for the articulation of the arms, by virtue of which the arms can be pivoted beyond the normal open position although they are returned to this position resiliently when released.
Within this field, it is known to produce frames in which a tie rod is hinged an the shoulder and engaged for sliding in a sheath of the arm, and a spring acts between the tie rod and a stop element guided for sliding on the tie rod and fixed to the sheath. A spectacle frame having the features outlined above is also known from U.S. Pat. No. 5,406,339. A spectacle frame having the features outlined above is also known from U.S. Pat. No. 5,406,339.
However, to ensure a sufficiently firm connection, the stop element is fixed to the art by a screw element, thus imposing serious technical limitations on the production of the entire arm in plastics material and consequently detracting from the breadth of the potential production range of the frame.
Moreover, the above-mentioned screw element in of somewhat small dimensions, making the assembly of the components of the system for articulating the arm to the shoulder quite awkward.
The problem upon which the present invention is based is that of providing a spectacle frame which has arms that can be opened out resiliently and which is designed structurally and functionally to overcome the limitations explained above with reference to the prior art mentioned.
Within the scope of this problem, a further object of the invention is to provide a frame which has a limited number of components and a low production cost, and which is easy to assemble.